Object A, having mass $m _ { A }$, is connected to object $\mathrm { B }$, having mass $m _ { B }$, by a massless cord. An upward force $P$ is applied to mass A, causing both masses to accelerate upward. Find the tension in the massless cord.
A) $P \times \left[ m _ { A } / \left( m _ { A } + m _ { B } \right) \right]$
B) $P \times \left[ \left( m _ { A } + m _ { B } \right) / m _ { B } \right]$
C) $P \times \left[ m _ { B } / \left( m _ { A } + m _ { B } \right) \right]$
D) $P \times \left[ \left( m _ { A } + m _ { B } \right) / m _ { A } \right]$

Question

Quizplus · Accepted Answer

The tension in the cord is equivalent to the force needed to lift mass B alone, since mass A is directly acted upon by force P. This force is a fraction of P, proportional to mass B's share of the total mass, hence $P \times \left[ m _ { B } / \left( m _ { A } + m _ { B } \right) \right]$.

Object A, Having Mass mAm _ { A }mA​ , Is Connected to Object

Object A, Having Mass $m _ { A }$ , Is Connected to Object